Process for the precipitation of precious metals from cyanid solutions.



STATES PATENT JAMES MILLAR NEIL, or 'ronou'ro, ou'r'amo, CANADA, assxeuon TO an a i HAY, or measure, omens.

rnocsss Fon' THE ranozrrrawlou or PRECIOUS METALS rnom cramp, semi-axons,

No Drawing.

T 0 all whom it may concern;

Be itlmown that I, JAMES M. Nani, of

Toronto, in the county of York, Province'of Ontario,'Canada, have invented certain new and useful Improvements in Processes for the Precipitation of'Pr'ecious Metals from Cyanid Solutions; and I hereby declarethat,

dite the precipitation of the precious metals efficiently; thanhas'f and recover ti'em m'ore" heretofore been done. r

Heretofore the ores containing precious n'ietals' havebeentreated with cyanid and the'preciousvmetals thereby dissolved in the cyanid solutions and thereafter the precious metals have been precipi'tatedfrom such so: lutions in various wa s,-'-- com'mo'nly by er; colation of the solution through" z1nc s avings, or by adding zinc-dust to the solution while in agitation. Zinc dust is an impure powder consistingof niore'or less metallic zinc, and impurities, the latter beirigin'ertfias' precipitating agents. I have discovered that when atomized lead, in metallic form, and Zinc dust are both added to a cyanid solution, in agitation, containing precious metals, the latter are precipitated more rapidly and efiiciently than when zinc dust is used alone; and I-' have further discovered that when atomized lead and atomizedzinc are both added, in metallic form, tothe c anid solution in agitation a still more rapi and eflicient reclpitation of the precious metals takes p ace.

The means for and method of'finely subdividing or atomizing the lead and zinc used in my process is not an essential part of my present invention. By atomized lead,.or atomized zinc I do not refer to metallic lead or zinc in their atomic form as supposed to exist in chemistry, but I mean lead,

,or zinc, finely subdivided so that it resembles a floury 'or substantially impalpable powder, yet not oxidized,

In the carrying out of my process atomized metallic lead and zinc dust may be used, but, preferably, in order to obtain the best results, atomized lead and atomized zinc (both in metallic form) should be used, in the proportion of about one part'of lead to one or more parts of zinc. These may be Specification of Letters Patent. Application filed September 5, 1911. Serial No. 647,734.

-o'f the zinc used is rarely obtir'me' Patented Apr, 16,1912.

mixed and added to the'cyanidsolution ntaining the precious metal's';in," fi2h ma" as isat present done in case offz s F or in any other suitable Mammy I add them separately tasjliereiiiafter"deg" scril)'ed', whereupon an electro-galvanic ac;

tion is set up between the lead and amino ducing a rapidaii'd efii'cie'nt'f'prjecipitati m of the precious metals, the nine oing int" solu-i' 7 tion and'replacing theilatte'r; whilethe lead f remaining unaltered, form spartgof{the'pre l cipitates. i

In practice when ziudtlus't-isiisedatone for the precipitation of the 'p'recitilis "etals from cyanid' solutions, fan sane-newer '7'. i a .F e e' b using atomiad lead ahdatomized it; is possible b get-an 'eflicieiicyof titer- 95% .ofi

the zinc used, and I havefoundtlitif the'fbI lowing method is a very'simpleaprdeitective one to use in the carrying'out'of j process and invention, and is one whereby eiii'ciencies of 95% and oi 'er' maybeobtiiiiied'i'n practice. x The cyliriid solution coining from the slimes filter is run into a suiliible' tankor container provided witha'ii zig i-tating"de vice. After a known quantity of-cyanfld solution, (the value of the'predate:metals; therein ha'vin been previously ascertain-ed I by analysis) as been putinto th'e tankf' there is then added thereto-wquantity of atomized lead; the amount thereof "may be" varied, but I have found that'an economic basis of'operation is'to supplyabout one hundred pounds of atomized lead-to about ten thousand gallons of cyanid solution. After adding the atomized leadthe contents of the" tank are thoroughly agitatedg aiid while in agitation I add thereto-preferably gradually or in small quantities at a time-- atomized zinc until the usual tests of the solution show that all of the precious motels therein have been precipitated. Zinc dust may be used in the process instead of the atomized zinc. When the precious metals have been precipitated the contents of the removing the precipitates which contain the lead in metallic form, and the whole again agitated; whereupon zinc either in an atomized orfinely divided form or as zinc dust is a ain added thereto, and the PIGCIOUS' any additional lead being supplied; until scribed novel cipitating precious metals cipitating' precious metals it becomes desirable to remove the lead gold and silver sludge. Such sludge may be separated from the solution, by filtration, or

by other suitable means, and then refined, the lead contained in the recipitates acting as a valuable agent in t e final treatmentthereof. p

By this process the preci itation of the precious metals is accomplis ed more rapidly, more'efliciently and with less consumption of zinc than by other methods.

I do not herein claim broadly the use of atomized lead in the process :of precipitating reciousmetals from cyanid-solutions, as t at is,cove'red in my application filed May 27, 1911, Serial No. 629,812; but in the present case I desire to cover the above demethod or process of treating cyanid solutions with atomize'd lead and Z1110. e

What I claim is :v

1. The herein described rocess of prerom cyanid solutions; consisting. in adding to the cyanid solution a substance containing atomized lead, agitating the solution and adding thereto a finely divided metallic precipitant.

2. The herein described rocess of precipitating' precious metals rom cyanid solutions; consisting-in adding to such a solution atomized lead, agitating the solution,-

and-adding thereto a finely divided sub stance containing zinc;

3. The herein described rocess of prerom cyanid solutions; consisting in adding to a cyanid solution atomized lead, agitating the solution and while it is in agitation adding thereto atomized zinc.

4. The herein described process of precipitating precious metals from cyanid sotion, and while it is in agitation successively adding thereto small quantities of a finely divided metallic preci itant, until the precious metals in the so ution have been precipitated, then removing the arren solution and recovering the precious metals contained in the precipitates.

5. The herein described cipitating precious metals lutions; consisting in adding tion a tatin finel g unti have beenprecipitated; then removing the barren solution; refilling the tank with fresh cyanid solution one or more times, agitating same, and adding more of the zincsubstance until the precious metals in the fresh solution are precipitated, then removing the barren solution and recovering the precious metals contained in the precipitates.

6. The herein described process of precipitating precious metals from cyanid solutions; consisting in adding to such solution a quantity of atomized lead; then agitating the precious metals in such solutionthe solution and while it is in a itation adding thereto atomized zinc until t e precious metals in the solution have been prec pitatedfthen removing the barren solutlon: refilling the tank with fresh cyanid solution one or more times, agitating same, and adding atomized zinc until the precious metals in the fresh solution are precipitated, then removing the barren solution and recovering the precious metals contained in'the precipitates.

In testimony that I claim the foregoing as my own, I afiix my signature in presence of two witnesses.

JAMES MILLAR NEIL.

lVitnesses:

MARTIN GRAHAM, LAWRENCE J. PASHLER. 

